1. Field of the Invention
The present invention relates to a method for growing a non-polar (13 40) plane epitaxy layer of wurtzite structure semiconductors with a single crystal oxide as a substrate, particularly to a method for growing a non-polar (13 40) plane epitaxy layer of zinc oxide or Group III nitride with wide band gap, low lattice mismatch, and high thermal stability. The present invention also provides an epitaxy layer having a non-polar (13 40) plane.
2. Description of Related Art
GaN and its related nitrides have received great attention in recent years due to the successful application in solid light emitting devices and laser diodes. These nitrides belong to a wurtzite crystal structure of hexagonal crystal system, which mainly grows in a direction along c axis. Prior studies show that GaN grown in the direction along c axis may present a planar arrangement and induce a built-in electric field by polarization effect, which in turn, results in the offsets of valence band and conduction band, thus reducing the light-emitting quantum efficiency.
Therefore, it has become an important development direction in industries to grow a non-polar plane, such as GaN of m-plane and a-plane to eliminate the polarization effect for promoting the quantum efficiency of a solid light-emitting device. There have been numerous excellent achievements in promoting the light-emitting efficiency of devices by using non-polar crystal plane to eliminate spontaneous polarity of GaN quantum well light emitting devices.
On the other hand, similar to GaN or other Group (III) nitrides, ZnO also has a high potential for laser applications due to the higher exciton binding energy (60 meV). However, ZnO and GaN materials have the same wurtzite structure, and the development of non-polar plane is needed for zinc oxide to overcome the problem of low light-emitting quantum efficiency.
In the prior studies, there have been many researches on non-polar plane GaN and ZnO grown by heterogeneous nucleation. In conclusion, a-plane GaN and ZnO single crystal can successfully grow on a r-plane sapphire substrate. M-plane GaN and ZnO single crystal can epitaxially grow on a m-plane silicon carbide substrate, a m-plane sapphire substrate and a γ-LiAlO2(100) substrate.
Therefore, it would be a great advance in the field of solid light emitting element to grow a novel non-polar crystal plane with better crystal and material properties than the existing non-polar a-plane and m-plane.